The FBI is investigating a surgical device that was found to spread cancer in women, including looking into what the largest manufacturer of it, Johnson & Johnson, knew about the tool’s hazards before pulling it off the market last year, according to people who have been interviewed by the agency.

It is unclear what stage the inquiry is in. The Federal Bureau of Investigation’s Newark, N.J., office, which is overseeing the investigation according to the three people interviewed, declined to comment.